//1.条件递增

for var index = 0; index < 3; ++index {

    println("index is \(index)")

}

//2.for in循环

//  2.1有变量名

for index in 1...5 {

    println("\(index) times 5 is \(index * 5)")

}

//  2.2没有变量名,如果不需要知道区间内每一项的值，你可以使用下划线（_）替代变量名来忽略对值的访问：

let base = 3

let power = 10

var answer = 1

for _ in 1...power {

    answer *= base

}

//  2.3遍历数组

let names = ["Anna", "Alex", "Brian", "Jack"]

for name in names {

    println("Hello, \(name)!")

}

//  2.4遍历字典

let numberOfLegs = ["spider": 8, "ant": 6, "cat": 4]

for (animalName, legCount) in numberOfLegs {

    println("\(animalName)s have \(legCount) legs")

}

//  2.5遍历字符串的字符

for character in "Hello" {

    println(character)

}

//1.while循环

let maxValue = 100

var x = 0

while x < maxValue {

    x++

}

println(x)  //100

//2.do while循环

var y = 0

do {

    y++

} while y < maxValue

println(y)  //100

var checkValue = 10

//1.if

var x = 1

if x < checkValue {

    println("x < 10")

}

//2.if else

var y = 15

if y < checkValue {

    println("y < checkValue")

} else {

    println("y >= checkValue")

}

//3.elseif

var z = 10

if z < checkValue {

    println("z < checkValue")

} else if z > checkValue {

    println("z > checkValue")

} else {

    println("z = checkValue")

}

//1.普通匹配

let someCharacter: Character = "e"

switch someCharacter {

case "a", "e", "i", "o", "u":

    println("\(someCharacter) is a vowel")

case "b", "c", "d", "f", "g", "h", "j", "k", "l", "m",

"n", "p", "q", "r", "s", "t", "v", "w", "x", "y", "z":

    println("\(someCharacter) is a consonant")

default:

    println("\(someCharacter) is not a vowel or a consonant")

}// 输出 "e is a vowel"

//2.区间匹配

let count = 200

var naturalCount: String

switch count {

case 0:

    naturalCount = "0"

case 1...10:

    naturalCount = "a few"

case 10...100:

    naturalCount = "several"

case 100...999:

    naturalCount = "hundreds of"

case 1000...999_999:

    naturalCount = "thousands of"

default:

    naturalCount = "millions and millions of"

}

println("There are \(naturalCount).")// 输出 "There are hundreds of."

//3.(Tuple)元组匹配可以使用元组在同一个switch语句中测试多个值。元组中的元素可以是值，也可以是区间。另外，使用下划线（_）来匹配所有可能的值。

    // 以2*2的坐标区间为例

let somePoint = (1, 1)

switch somePoint {

case (0, 0):

    println("(0, 0)在原点")

case (_, 0):

    println("(\(somePoint.0), 0)在x轴")

case (0, _):

    println("(0, \(somePoint.1))在y轴")

case (-2...2, -2...2):

    println("(\(somePoint.0), \(somePoint.1))在2*2区域内")

default:

    println("(\(somePoint.0), \(somePoint.1))在2*2区域外")

}// 输出 "(1, 1)在2*2区域内"

    //值绑定:可以将元组中的值临时绑定到一个变量中

let anotherPoint = (2, 0)

switch anotherPoint {

case (let x, 0):

    println("在x轴,且x坐标值为:\(x)")

case (0, let y):

    println("在y轴,且y坐标值为:\(y)")

case let (x, y):

    println("坐标点:(\(x), \(y))")

}// 输出 "在x轴,且x坐标值为:2"

    //case 分支的模式可以使用where语句来判断额外的条件。

let yetAnotherPoint = (1, -1)

switch yetAnotherPoint {

case let (x, y) where x == y:

    println("(\(x), \(y)) 在x == y的直线上")

case let (x, y) where x == -y:

    println("(\(x), \(y)) 在x == -y的直线上")

case let (x, y):

    println("(\(x), \(y)) 不在对称线上")

}// 输出 "(1, -1) 在x == -y的直线上"

//1.continue

for i in 1...10 {

    if i%2 == 0 {

        continue //整除2就直接进入下一次循环

    }

    print("\(i) ")

}   // 输出1 3 5 7 9

//2.break

for i in 1...10 {

    if i%3 == 0 {

        break //整除3就直接跳出for循环

    }

    print("\(i) ")

}   // 输出1 2

println("")

//3.fallthrough 贯穿

/*Swift 中的switch不会从上一个 case 分支落入到下一个 case 分支中。相反，只要第一个匹配到的 case 分支完成了它需要执行的语句，整个switch代码块完成了它的执行。相比之下，C 语言要求你显示的插入break语句到每个switch分支的末尾来阻止自动落入到下一个 case 分支中。Swift 的这种避免默认落入到下一个分支中的特性意味着它的switch 功能要比 C 语言的更加清晰和可预测，可以避免无意识地执行多个 case 分支从而引发的错误。

如果你确实需要 C 风格的贯穿（fallthrough）的特性，你可以在每个需要该特性的 case 分支中使用fallthrough关键字。下面的例子使用fallthrough来创建一个数字的描述语句。*/

let integerToDescribe = 5

var description = "数字 \(integerToDescribe) 是"

switch integerToDescribe {

case 2, 3, 5, 7, 11, 13, 17, 19:

    description += "一个质数, 也是一个"

    fallthrough

case 1, 3, 5, 7, 9, 11, 13, 15, 17, 19:

    description += "奇数, 也是一个"

    fallthrough

default:

    description += "整数"

}

println(description)

// 输出 "数字 5 是一个质数, 也是一个奇数, 也是一个整数."

let maxValue = 100

let flagValue = 55

let stepValue = 10

var i = 5

addLoop: while i < maxValue {

    i = i + stepValue

    switch i {

    case flagValue:

        println("到达标示的数字,退出wile循环")

        break addLoop

    case 1...10:

        println("数字\(i)介于1到10之间")

    case 11...20:

        println("数字\(i)介于11到20之间")

    case 21...30:

        println("数字\(i)介于21到30之间")

    case 31...40:

        println("数字\(i)介于31到40之间")

    case 41...50:

        println("数字\(i)介于41到50之间")

    case 51...60:

        println("数字\(i)介于51到60之间")

    default:

        println("Default")

    }

}